1. Field of the Invention
The present invention relates to a weight system for a golf club head. In particular, the present invention relates to a vibration-absorbing weight system for a golf club head.
2. Description of Related Art
U.S. Pat. No. 5,290,036 discloses a cavity back iron with vibration damping material in the cavity. As illustrated in FIG. 1 of the drawings, the golf club disclosed in U.S. Pat. No. 5,290,036 comprises a head 100 including a striking face 101 and a back cavity 102, which is substantially filled with polyurethane 200 (or damping material). When striking a golf ball with the golf club, the damping material 200 may absorb residual vibrations and thus improve gripping comfort.
To improve striking accuracy and direction controllability of the golf ball, when the golf ball begins to contact with the striking face 101, the striking face 101 should be rapidly and significantly compressed when subjected to a slight striking momentum, and the striking face 101 should rapidly resume its shape when the golf ball is about to leave the striking face 101, creating a greater restoring force to be imparted to the golf ball. The striking face 101 creates a rearward stress during continuous deformation of the striking face 101, which causes compression of the damping material 200.
However, since the damping material 200 has a low elastic deforming capability, in the beginning of deformation of the striking face 101, the damping material 200 overpresses against the striking face 101 and thus adversely affects the striking effect. Further, from the time of initial contact between the head 100 and the golf ball to the time the ball leaves the head 100, the striking face 101 could not effectively flex rearward to prolong the contact time with the golf ball due to overpressing by the damping material 200. Thus, the damping material 200 fails to provide the best damping effect, and the overall striking effect is significantly affected.
To adjust the center of gravity of a golf club head, it is common to mount at least one weight member to, e.g., a sole of a body of the club head by welding, screwing, press-fitting, etc. Such a design is disclosed in, e.g., U.S. Pat. Nos. 6,012,990; 6,206,790; 6,524,198; and 6,773,360. However, the club head with a weight member has a relatively small damping and provides an unsatisfactory vibration-absorbing effect. The joint area between the weight member and the club head is liable to crack after a period of time of use, leading to generation of odd sounds and even disengagement of the weight member.